Long-Term Obligations - Additional Information (Details) - USD ($)	12 Months Ended			36 Months Ended
	Jul. 31, 2016	Jul. 31, 2015	Jul. 31, 2014	Jul. 31, 2007	May 13, 2010
Line of Credit Facilities [Line Items]
Proceeds from lines of credit	$ 96,276,000	$ 83,382,000	$ 73,334,000
Repayments on line of credit	91,759,000	32,314,000	$ 62,398,000
Debt Instruments [Abstract]
Letters of credit outstanding	$ 4,261,000	3,327,000
Ratio Of debt to EBITDA	equal to 1.4 to 1.0
Interest expense coverage ratio	equal to 19.9 to 1.0
Long-term debt, fair value	$ 218,977,000	252,254,000
Long-term debt less notes payable	211,982,000	$ 243,288,000
Private Placement [Member]
Debt Instruments [Abstract]
Debt face amount					$ 75,000,000.0
Debt instrument aggregate face amount during period				$ 350,000,000
Debt instrument, interest rate terms				from 5.30% to 5.33%
Repayments of long-term debt	$ 42,500,000
Euro-denominated notes payable in 2017 at a fixed rate of 3.71% [Member]
Debt Instruments [Abstract]
Debt face amount					30,000,000.0
Long-term debt, fixed interest rate percentage	3.71%
Euro-denominated notes payable in 2020 at a fixed rate of 4.24% [Member]
Debt Instruments [Abstract]
Debt face amount					$ 45,000,000.0
Long-term debt, fixed interest rate percentage	4.24%
USD-Denominated Borrowing Credit Revolver [Member]
Line of Credit Facilities [Line Items]
Line of credit, current borrowing capacity	$ 300,000,000
Line of credit, maximum borrowing capacity	450,000,000
Line of credit facility, maximum amount outstanding during period	135,000,000
Proceeds from lines of credit	10,000,000
Line of credit, remaining borrowing capacity	183,739,000
Line of credit facility, maximum remaining borrowing capacity	333,739,000
China line of credit facility [Member]
Line of Credit Facilities [Line Items]
Line of credit facility, maximum amount outstanding during period	10,411,000
Repayments on line of credit	5,483,000
Line of credit facility, amount outstanding	4,928,000
Line of credit, remaining borrowing capacity	15,072,000
Lender 1 [Member] | China line of credit facility [Member]
Line of Credit Facilities [Line Items]
Line of credit, current borrowing capacity	$ 10,000